1. Field of the Invention
The present invention relates to a protective device for window panes which are susceptible to scratching, particularly the rear window panes in folding convertible tops. The pane is at its circumference welded into an envelope of covering material which forms a window frame. In addition, the covering material is sewed together with the window pane. During the manufacture and assembly of the convertible top, the window pane is provided with a cover of a material which is mechanically weak but soft and neutral relative to the pane material, for example, a non-woven fabric, and of a foil having a high mechanical strength.
2. Description of the Prior Art
Window panes in motor vehicles must meet a variety of requirements which are in part contradictory. This is particularly true in so-called safety panes, especially in rear window panes of folding convertible tops. These window panes must have good optical properties in order to ensure a clear and distortion-free view. Also, the panes must have sufficient stiffness, so that they assume a non-wavy shape when in the tensioned state, i.e., when the convertible top is closed. On the other hand, the panes must have sufficient flexibility, so that, since they are integrated into the top of the convertible, they can follow the folding procedure of the top when the top is opened, without suffering buckling or permanent deformations.
Therefore, the window panes used in rear windows of folding convertible tops are made of a plastics material which has excellent optical properties, particularly affording a clear view, and, on the other hand, has sufficient flexibility in order to follow the folding process during opening of the top. However, the materials known and available for the manufacture of such window panes have the disadvantage that they are extremely susceptible to scratching, so that the danger exists, that the panes are damaged already during the manufacturing and assembling process of the convertible top and, thus, the optical properties and particularly the clear view are significantly impaired.
In addition, the materials known and used in the manufacture of window panes and particularly of rear window panes in convertible tops are extremely sensitive with respect to adhesives, so that it is not possible to glue a protective cover onto the window pane for protecting the pane during the manufacturing and assembling procedure of the convertible top.
In order to avoid the above-described difficulties resulting from the properties of the materials used for the manufacture of window panes in convertible tops, the window panes in convertible tops have in the past been covered on both sides by means of a cover of a soft material which is neutral with respect to the material of the window pane, particularly a non-woven fabric, and of an additional foil of tear-resistant material. This cover was fastened by means of adhesive tape to the material of the convertible top at the circumferential edge of the window pane. Of course, this solution, which requires the application of two different cover materials one on top of the other and gluing the cover materials by means of special adhesive tape to the material of the convertible top, is expensive with respect to material and labor. This increases the manufacturing costs of the convertible top.
It is, therefore, the primary object of the present invention to provide a protective device for a window pane of a convertible top, particularly the rear window, which is inexpensive and safe to manufacture.
It is another object of the present invention to provide a protective device which makes it possible to protect a window pane, particularly a rear window pane of a convertible top, against all types of damage until the vehicle is delivered, without foregoing the possibility of checking the window pane as it is delivered to the vehicle manufacturer.